add some log

Signed-off-by: bowenlan-amzn <[email protected]>

server/src/main/java/org/opensearch/search/aggregations/metrics/CardinalityAggregator.java

@@ -32,6 +32,8 @@
 
 package org.opensearch.search.aggregations.metrics;
 
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.index.SortedNumericDocValues;
 import org.apache.lucene.index.SortedSetDocValues;
@@ -81,6 +83,8 @@
  */
 public class CardinalityAggregator extends NumericMetricsAggregator.SingleValue {
 
+    private static final Logger logger = LogManager.getLogger(CardinalityAggregator.class);
+
     private final int precision;
     private final ValuesSource valuesSource;
 
@@ -279,6 +283,7 @@ public void close() {
         @Override
         public void collect(int doc, long owningBucketOrd) throws IOException {
             delegate.collect(doc, owningBucketOrd);
+            logger.debug("collect doc {}", doc);
 
             DisiWrapper top = queue.top();
             int curTopDoc = top.doc;
@@ -288,6 +293,8 @@ public void collect(int doc, long owningBucketOrd) throws IOException {
                     top = queue.updateTop();
                 } while (queue.size() > 1 && top.doc == curTopDoc);
             }
+
+            logger.debug("after pruning top doc {}", top.doc);
             // after pruning, queue top doc will exceed current doc
             // but in the scoring process, we have a contract that every iteration or nextDoc
             // iterator: 0 - 1 - 2 - 3 - ...